1. Field of the Invention
The present invention relates to a fluorescent display panel for giving a sense of perspective or relief image.
2. Description of the Prior Art
A typical form of fluorescent display panel includes an anode substrate having anode segments coated with phosphor, a cathode member placed over the anode segment, and a grid member disposed between the anode segments and the cathode member. A cover glass is secured to the anode substrate. Such a configuration is fully described by Takao Kishino in U.S. Pat. No. 4,047,073 (Patented on Sept. 6, 1977). In operation, only those anode segments which are held at a positive potential are excited to emit light by a bombardment of the electrons emitted from the cathode member and accelerated by the grid member potential. The emitted electrons display any shape of a display pattern according to the pattern of the anode segments such as a desired numeral, letter or figure.
Since such a display pattern is observed from the side of a cover glass, inevitably, it has a narrow viewing angle. To this end, a new structure has been developed such that the anode segment on a transparent substrate has a mesh structure to pass the light emitted from the phosphor coated thereon. Thus a display pattern can be observed from the side of the transparent substrate with a wide viewing angle. This new structure is reported by Y. Yoshida et al in "Latest Technology, in FIP" on pages 73 to 77 of SAE Technical paper 830045, delivered on Feb. 28, 1983. Although many improvements for a display quality have been made, the observable display pattern has been nothing but a plane figure. If the plane figure is turned into a figure appearing to be a solid, the display panel becomes more attractive.